Study On The Adsorption Mechanism Of Anionic And Cationic Mixed Collectors On Fluorite And Calcite Surfaces

In this paper,the adsorption mechanism of an anion-cation mixed collector composed of cationic collector cetyltrimethylammonium bromide（CTAB）and anion collector styrene phosphonic acid（SPA）on fluorite and calcite surfaces was studied.The solution properties of the mixed collectors were studied by surface tension and pyrene fluorescent probes,and the adsorption mechanism of the mixed collectors on fluorite and calcite surfaces was revealed by surface potential analysis,contact angle analysis and chemical adsorption morphology.Finally,the change of the interaction force between fluorite and calcite particles was analyzed from the perspective of interfacial force.The following conclusions were obtained in this paper:（1）Single mineral flotation experiments showed that the flotation separation effect of mixed collectors was better than single collectors.The optimal flotation conditions were:pulp p H=10～11,molar ratio M_CTAB:M_SPA=1:1,mixed collector concentration C=1×10^-4 mol/L.（2）Surface tension and pyrene fluorescent probe analysis showed that the mixed collectors could significantly reduce the surface tension and critical micelle concentration（CMC）of the solution.The order of CMC values in different collector systems was:mixed collector(M_CTAB:M_SPA=1:1)>CTAB>SPA.When the mixed collector was mixed in equal proportion,the Gibbs free energy was the smallest and the surface properties of the solution were the best.（3）The surface potential analysis showed that the mixed collectors caused a large change in the surface potential of fluorite in the entire p H range,and co-adsorption occurred on the surface of fluorite.Contact angle studies showed that the mixed collectors could significantly increase the surface contact angle of fluorite.The mixed collectors increased the contact angle difference between fluorite and calcite to26.7°,which enlarged the difference in surface hydrophobicity.The adsorption morphology of the agent showed that the single collector was inclined to adsorb on the surface of fluorite and calcite.The adsorption capacity of the mixed collector on the surface of fluorite was greater than single collector,and the adsorption was uniform point-like.（4）The study of force between particles showed that collectors affected the force between particles by changing the hydrophilicity and hydrophobicity of mineral surfaces.At low concentration,the adsorption of the collector on the surface of the mineral enhanced its surface hydrophobicity,and the hydrophobic attraction became dominant,which enhanced the attraction between particles.The attraction between fluorite particles reached the maximum when the CTAB concentration was 1×10^-4mol/L,and the maximum attraction was 5.07 n N.If the concentration was too large,the collector formed multi-layer adsorption on the mineral surface,and the hydrophobic attraction also decreased.The adhesion force between particles increased with the increase of concentration,but does not decrease.Solution p H affected the interaction force between particles by affecting the mineral surface potential.Fluorite and calcite were positively charged in acidic and weakly alkaline environments,and negatively charged in strong alkaline environments.Therefore,CTAB was easily adsorbed on the mineral surface in an alkaline environment,the attraction between fluorite particles was the largest at p H=11,which was 5.07 n N.SPA was easily adsorbed on the mineral surface in an acidic environment,and the attraction between fluorite particles was the largest at p H=3,which was 2.68 n N.The synergistic adsorption of the mixed collector on the fluorite surface strengthens the hydrophobicity of the fluorite surface and the association between molecules.The attraction force between particles,the"jump-in"distance and the adhesion force were larger than single collector.The attraction and adhesion between fluorite particles were greater than calcite,which was conducive to the stability of the fluorite agglomeration system.